1. Field of the Invention
The present invention relates to a controller for an image processing apparatus which controls input/output devices by a pulse control signal such as pulse width modulation (PWM).
2. Related Background Art
Recent developments in the industries of office automation (OA) and factory automation (FA) has been remarkable. It may be a result of fine combination of electronics and mechanics. Needless to say, a base thereof greatly depends on mutual effect of the development of semiconductor integration technology and computer technology. A population of large amount of goods produced in an inexpensive manner largely depends on LSI implementation of the system.
Many of existing controllers use microcomputers or microcontrollers (one-chip microcomputer including a memory and I/O). However, many discrete parts are required to combine the machine and the controller, it may be superfluous. This is due to continuous change of an analog quantity in mechanical technology or in the natural field, especially. As an approach to solve the above problem, a one-chip microcomputer which has on-chip A/D converter or PWM output has been proposed. However, it is still insufficient to grasp a change of analog quantity in the natural field and feed an analog signal back to suppress the change, and in actual many separate controllers are externally provided. This increases a cost, which is due to a large number of types of analog signals to be fed back and lack of systematic control.